Announcement

Collapse
No announcement yet.

Macbook 820-3115 missing 3V42_G3H

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #41
    Re: Macbook 820-3115 missing 3V42_G3H

    Greenlight is on with 3,4V on Pin 2 of L6995
    That is expected and a good sign. U6990 and linked local parts create this 3v42 rail. This rail is required to turn on the magsafe LED (green / orange). The color of the led is over a single wire communication protocol.


    without U7491 even attached.
    U7491 is another component that is powered off the 3v42 rail.

    Remove all power -> meter in lowest resistance scale -> what is the resistance to ground of PPBUS_G3H ?

    Comment


      #42
      Re: Macbook 820-3115 missing 3V42_G3H

      PPBUS_G3H is at 4,5 Ohms

      Comment


        #43
        Re: Macbook 820-3115 missing 3V42_G3H

        PPBUS_G3H is at 4,5 Ohms
        That is too low.

        Remove F7040 (fuse) and check which side of the fuse pads is with the low resistance.

        Is the short on the producer side (L7030 inductor) or consumer side (pin # 2 of F7040) ?

        Do not power up, only remove the fuse to locate the side with the short.

        Comment


          #44
          Re: Macbook 820-3115 missing 3V42_G3H

          Its Pin 2 of F7040

          Comment


            #45
            Re: Macbook 820-3115 missing 3V42_G3H

            Power up without the same fuse and confirm that PPBUS_G3H is present.

            What is the voltage on pin #1 of this fuse pad (F7040) ?

            Comment


              #46
              Re: Macbook 820-3115 missing 3V42_G3H

              It starts at 1,3 V but is declining.
              Last edited by Nuld_; 06-26-2022, 10:34 AM.

              Comment


                #47
                Re: Macbook 820-3115 missing 3V42_G3H

                Remove all power. Check the resistance to ground of fuse pad #1. Checking for shorted caps.

                What is the resistance?

                Comment


                  #48
                  Re: Macbook 820-3115 missing 3V42_G3H

                  Pin 1 is reading O.L

                  Comment


                    #49
                    Re: Macbook 820-3115 missing 3V42_G3H

                    What is the meter scale ? OL is a good sign that you do not have any bad caps on this (producer) side.

                    Confirm the voltage of PPCHGR_DCIN, ACIN, PPDCIN_G3H_CHGR.

                    If the voltage is powering U7000 and arriving at the high side mosfet, the next step is to confirm the mosfets are OK with resistance checks.

                    For the mosfet resistance checks, remove all power and check the resistance readings across the mosfet pins (Q7030):

                    Source (1-2-3) & Drain (5-6-7-8)
                    Source (1-2-3) & gate (4)
                    gate (4) & Drain (5-6-7-8)

                    Post each reading & the scale used on the meter.

                    Then repeat the measurements for the low side mosfet @ Q7035.

                    If the mosfet readings are not too low then it is down to U7000 being defective and needs to be replaced.

                    Without the fuse onboard, the PPBUS_G3H should be text boot perfect on pin # 1 of the (removed) F7040 fuse.

                    need to grab some groceries..will check back later...
                    Attached Files

                    Comment


                      #50
                      Re: Macbook 820-3115 missing 3V42_G3H

                      PPCHGR_DCIN: 16,55V
                      CHGR_ACIN: 3,97V
                      PPDCIN_G3H_CHGR: 16,4V

                      Q7030:
                      Souce-Drain: 4Mohms (Mohms)
                      Source-Gate: 1Ohms (Ohms)
                      Gate-Drain: 9,5Mohms (Mohms)

                      Q7035:
                      Souce-Drain: 4Mohms (Mohms)
                      Source-Gate: 5kOhms (Ohms)
                      Gate-Drain: O.L (Mohms)

                      Comment


                        #51
                        Re: Macbook 820-3115 missing 3V42_G3H

                        omg, it was hot outside..my milk duds were sweating. should burn the lawn and collect insurance.


                        Q7030:
                        Souce-Drain: 4Mohms (Mohms)
                        Source-Gate: 1Ohms (Ohms)
                        Gate-Drain: 9,5Mohms (Mohms)
                        The part is most definitely shorted and needs to be replaced. You can remove it off the board and check these measurements again on the removed component. Unless the ISL is causing this short condition, the mosfet should be replaced.

                        Q7035:
                        Souce-Drain: 4Mohms (Mohms)
                        Source-Gate: 5kOhms (Ohms)
                        Gate-Drain: O.L (Mohms)
                        Also consider to replace this part as the resistance is low. Compare the value against a fresh mosfet.

                        These parts are very inexpensive so consider to buy spares and replace these 2 mosfets and do source also the regulator @ U7000 as a precaution. If you have a donor board, even better.

                        After the replacements, still leave off the fuse @ F7040 and confirm that PPBUS_G3H is restored.

                        Comment


                          #52
                          Re: Macbook 820-3115 missing 3V42_G3H

                          Q7030:
                          Souce-Drain: 4Mohms (Mohms)
                          Source-Gate: 20kOhms (kohms)
                          Gate-Drain: 9,5Mohms (Mohms)

                          Q7035:
                          Souce-Drain: 4Mohms (Mohms)
                          Source-Gate: 5kOhms (Ohms)
                          Gate-Drain: O.L (Mohms)

                          Compered to another Board seems to be okay now.
                          But Pin 2 of F7040 is still reading around 5 Ohms.
                          Last edited by Nuld_; 06-27-2022, 11:11 AM.

                          Comment


                            #53
                            Re: Macbook 820-3115 missing 3V42_G3H

                            Is the a way to check if U7000 is alright ?

                            Comment


                              #54
                              Re: Macbook 820-3115 missing 3V42_G3H

                              Compered to another Board seems to be okay now.
                              The mosfets on this board match the mosfet resistance values of a working and identical logic board?


                              Is there a way to check if U7000 is alright ?
                              Yes, when ppbus_g3h is the proper value, u7000 is ok.

                              Comment


                                #55
                                Re: Macbook 820-3115 missing 3V42_G3H

                                It’s similar to the other defective logic board

                                Comment


                                  #56
                                  Re: Macbook 820-3115 missing 3V42_G3H

                                  Start with replacing the 2 mosfets. Before replacing, check their resistance while the parts are out of circuit.

                                  PPBUS_G3H (aka F7040, pin # 2) travels all over the board. Respectively, review for any possible damage to the circuit board; liquid damage / corrosion, etc.

                                  If none is found, only then proceed to use a power supply at a low voltage but can use higher current - suggest 0v8 on the voltage and 2-5A on the current. Will link a great video on this subject later today but it is from ADAMIT on how this works.

                                  Summary is that the shorted part will heat up as you inject this voltage. Hoping it is a bad cap downstream. We want to keep the voltage low in case the CPU power mosfets are linked to this rail and if the mosfets are shorted / leaking. A higher voltage will destroy the CPU.

                                  Comment


                                    #57
                                    Re: Macbook 820-3115 missing 3V42_G3H

                                    So I´ve removed both Mosfets and checked them, readings are:

                                    Q7035
                                    Source-Drain: 4,5 Mohms
                                    Source-Gate: O.L
                                    Gate-Drain: O.L

                                    Q7030
                                    Source-Drain: 9 Mohms
                                    Source-Gate: O.L
                                    Gate-Drain: O.L

                                    There is no obvious sign of liquid damage or something else.

                                    Where should I inject voltage?
                                    Last edited by Nuld_; 06-28-2022, 11:24 AM.

                                    Comment


                                      #58
                                      Re: Macbook 820-3115 missing 3V42_G3H

                                      Watch this video:

                                      https://www.youtube.com/watch?v=EWuzmIz7hOE

                                      Then with your power supply set to 0v8 (yes < 1v0), current @ 2A-5A should be ok, apply the red power supply lead onto PPBUS_G3H.

                                      Black power supply lead to ground. Check for any part that may be heating up. Hoping it is a capacitor like in the YT video.

                                      Do not increase the voltage - to protect the CPU in case it is shorted to the same rail.

                                      Comment


                                        #59
                                        Re: Macbook 820-3115 missing 3V42_G3H

                                        I´m struggeling with my power supply, I´ve set it to 0,8V but the maximum Current i can inject is about 0,191 A so nothing seems to heat up.

                                        Comment


                                          #60
                                          Re: Macbook 820-3115 missing 3V42_G3H

                                          Is there something i´m missing?

                                          Comment

                                          Working...
                                          X